In some valves, such as ball valves, fluid flowing through the valve may be subject to rapid changes in pressure, and this rapid pressure change in the fluid may result in the formation of vapor cavities in low-pressure portions of the fluid, a phenomenon known as cavitation. When the vapor cavities in the fluid are subjected to higher pressure, the vapor cavities implode and can generate an intense shock wave that can damage internal portions of the valve.
In valve embodiments in which cavitation is a danger, cavitation/aerodynamic control devices may be disposed in or adjacent to the inlet such that when the ball valve is in an open position, fluid flows from the inlet to the outlet through the cavitation/aerodynamic control device. The cavitation/aerodynamic control device may slow and/or isolate segments of fluid flow through the valve to slow the pressure reduction and/or increase in the fluid, thereby eliminating (or reducing the likelihood) of low-pressure areas in which vapor cavities can occur in the fluid. As a consequence, hydrodynamic noise may also be attenuated by the device.
In typical cavitation/aerodynamic control device assembly (such as the Emerson® Cavitrol® V tube bundle which is illustrated in FIG. 13C), a plurality of austenitic stainless steel tubes were bundled together, and the plurality of tubes was then surrounded by a metal shroud. The assembly may be vacuum brazed with, for example, a powdered metal paste silver brazing material (such as AWS A5.8 BAg-1). A flange may also be welded to the shroud to simplify mounting to a portion of pipe. However, with so many parts (e.g., typically over 300 tubes), the assembly is time consuming—and therefore expensive—to produce. In addition, such a tubing assembly is very difficult to produce with conventional manufacturing process (such as casting) and is cost prohibitive to machine with wire or ram-type electrical discharge machining. Accordingly, thicker tubes than optimally desired are used, and the effectiveness at reducing or eliminating cavitation is reduced while material cost is increased.